home audio system

[Stewart C. Russell]

On 13-12-13 11:26 AM, Lennart Sorensen wrote:
> 
> But the pi has hardware floating point.  Is it that bad or are you
> running the wrong kind of arm linux on it?

I just re-ran a test using lame 3.99.5 on two machines:

* encoding a wav file to mp3 using 'lame -V2' on a Raspberry Pi
(Raspbian armv6l) encoded at 2.2× real time

* the same file on my i7 laptop: 51× real time. And that was only using
one of its cores.

While it would be nice to have the GPU as a general media encoder, we're
not there yet. If you must encode mp3s quickly on a Raspberry Pi, there
are a couple of options:

* Comprec - http://unimut.fsk.uni-heidelberg.de/demi/comprec/index.html
  This uses ARM assembly language. The code is a little fiddly to
compile, but can encode to a 128 kbit/s mp3 in ~ 6× real time

* Shine - https://github.com/savonet/shine
  This is actually being maintained, and is portable between
architectures. Not quite as fast as comprec, at 2.7× real time. It's
screamingly fast on x86_64, btw.

Please note that both of these are based on the old '8hz' mp3 encoder,
which was a fairly literal interpretation of the original Fraunhofer
code. They only start producing okay sounding files at high bitrates.

If you need to decode mp3s quickly, MAD is pretty good:
http://www.underbit.com/products/mad

cheers,
 Stewart
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